Canadian Patents & Development Ltd.

Canadian Patents and Development Limited/societe Canadienne Des Brevets

Dennis K Lam

Robert I MacDonald

Julian P Noad

Photoconductors with channels that lie in the surface depleted region of a GaAs structure are described. These devices have nanoampere bias current, and exhibit photoconductive gain. In contrast to other photoconductors, their low frequency responsivity is of the same order as that in the GHz region, alleviating problems of equalization necessary in receiver applications. As well, these devices exhibit over 60 dB isolation as optoelectronic switches.

Depleted channel photoconductor

An optoelectronic assembly for converting a signal between optical and electrical form, or vice versa, consists of a dielectric substrate and a semiconductor substrate. These substrates are fabricated separately and then brought together with major faces in intimate contact with each other. The dielectric substrate has a pair of metallic electrodes on its surface and a waveguide extending to a coupling region. The semiconductor substrate has an active optoelectronic device, e.g. a photodetector or light emitting device, whose optically active portion is brought into optically coupling relationship with the coupling region of the waveguide. At the same time electrically contacting regions of the optoelectronic device are placed in electrical contact with respective ones of the pair of metallic electrodes on the dielectric substrate. In addition to the advantage of separate fabrication of the two substrates, with consequent avoidance of the process incompatabilities that arise when trying to form optical and electronic elements on the same substrate, the invention is especially well suited to the formation of large scale integrated optoelectronic circuits and switching networks.

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Dennis K Lam